


Sharing Is Caring

by AbsinthexMind



Series: Oh brother where art thou [43]
Category: Harry Potter - J. K. Rowling
Genre: Break Up, Breaking Up & Making Up, Brother/Sister Incest, Developing Relationship, Established Relationship, F/M, False Accusations, Getting Back Together, Getting to Know Each Other, Incest, Negotiations, Platonic Relationships, Polyamory, Polyamory Negotiations, Relationship Negotiation, Relationship(s), Sibling Incest, Threesome - F/M/M
Language: English
Status: Completed
Published: 2019-08-19
Updated: 2019-08-19
Packaged: 2020-08-14 12:49:40
Rating: Mature
Warnings: Underage
Chapters: 1
Words: 2,227
Publisher: archiveofourown.org
Story URL: https://archiveofourown.org/works/20192572
Author URL: https://archiveofourown.org/users/AbsinthexMind/pseuds/AbsinthexMind
Summary: Tumblr RequestYou had belonged to Regulus far before Sirius confessed his feelings. How would your selfish brother learn how to share you?





	Sharing Is Caring

Sirius pushes away Regulus’ face, instead placing his lips on your own. 

Furious, Regulus tries to push your older brother out of the way but the eldest of the Black siblings was physically stronger and taller than the other, not easily pushed away in other words. “It was my turn.” He hisses indignantly. “You always do this Sirius.” 

Not wanting them to fight, you place a hand on Sirius’ chest and look imploringly at your twin. “You guys-” 

“And you never share.” Not the least bit upset, Sirius grins and sticks his tongue out. He promptly goes back to nuzzling his face against your neck. 

“I shouldn’t have to. She was mine first.” 

It had taken a while for Regulus to agree to such an arrangement. Hell, at first he didn’t even want to consider it. He had always been terrible at sharing you with others, even if that included your friends and your older brother. He so often loved to tell you that the two of you didn’t need anyone else. You were born together for a reason. And you had thoroughly believed it when you were younger, that’s why you never had any friends except for Regulus. Well, besides Sirius. That was one person you wouldn’t budge on. You loved your older brother. He had always been a ready playmate when Regulus couldn’t be with you. Sirius made you laugh when you thought you would never laugh again. Regulus never liked it but you refused to treat him like the rest of your family did. 

You had a different love for Regulus than you did Sirius though. That was very clear from the day the two of you were born. Attached at the hip and wanting nothing more than to enjoy the company of the other. As the two of you grew and entered adolescence, your love for Regulus morphed into something different. Sibling love had become romantic. A shy kind of love that made your heart flutter when he was near and the kisses between you oh so delicious. As children you had always kissed him on the lips, childish in the early years. The kisses grew more hungry and were teeming with want and desire. Regulus’ innocent hand holding became possessive; especially when the two of you were finally old enough to enter Hogwarts. He was hyper aware of the other boys at the school, worried that they might wander too near to your heart. The two of you had never discussed this transition of your relationship. It was never necessary. You accepted it as it was without any question. The feelings you felt for Regulus couldn’t be bad. He was literally the other half of you. Your soulmate. 

No wonder at all when in your third year things started to change physically between the two of you. You would sneak off late at night, dodging professors and prefects alike just to steal some time with each other. Hands roamed in the dark and teeth began to grow courageous on your skin as Regulus physically marked you. Even in the daylight it was hard for you to keep your relationship a secret. There were always lingering glances that were not something siblings would exchange with one another. His hand would stay on your lower back for too long, even be caught traveling down to your rear. Not like anyone in your house would say anything against it. Regulus had made himself a reputation in Slytherin. Added bonus that the two of you were from a very well respected pureblood household like Black. Even if they wanted to say something, they would be too scared and rightfully so. 

Your life had been perfect. 

Until Sirius came up to you one day and confessed to you a secret. Something you would have never guessed. 

He confessed it with a kiss. A kiss right in front of Regulus. 

Needless to say your twin didn’t take it well. There was a fight right then and there with Regulus casting hex after hex trying to hit Sirius while your older brother on the other hand was desperately trying to verbally say his feelings about you. Nothing appeased Regulus and there had been a crowd gathering. Confused but not surprised as to why the brothers were fighting. You had stepped in, knocking Regulus’ wand out of his hands to protect Sirius. This did not go well either. He accused you of betraying him. Of cheating on him with Sirius. That you no longer loved him. All of which were untrue but in Regulus’ enraged state of mind he believed every single one of his delusions. 

He promptly stormed off and refused to talk to you for days. 

His cold demeanor toward you was incredibly painful. Never in your whole entire life had your brother treated you in such a way. You weren’t accustomed to being ignored by him. In all honesty it broke your heart. He didn’t believe you. Didn’t trust you enough when you had so much trust in him. 

And that’s when Sirius started to play a more profound romantic role. While Regulus was ignoring you, you gave an ear to Sirius. He explained to you more privately of how for the longest time he had tried to squash down his feelings for you. Ever since you had started to mature he had felt different. At first he had put it off as just a normal brotherly feeling of watching a sibling grow up before his eyes. He finally understood though when he came across you and Regulus at home. The two of you interlocked, assuming that no one else was there to witness your love for one another. 

“You have never felt ashamed for the way you felt for Regulus?” He had asked you one day. With no one else to hang out with at school, you opted for Sirius. You wanted an explanation for the entire mess he had caused. That conversation had led down another rabbit hole and you found yourself laying down in front of the Black Lake one evening. Sirius was beside you, watching the swell of fluffy clouds lazily roll by in the sky. 

You shook your head. “No. Never. It’s always been natural between us. I don’t see why I should feel ashamed even though I know there are people out there who might make me feel that way. Besides, incest is nothing new with our family.” 

“Huh. I guess you’re right.” Sirius rolled onto his side to look at you, endearment casting a light upon his otherwise dark eyes. “You really are a lot more mature than Regulus and I. You know who you are and don’t feel an ounce of guilt.” 

“Neither do you. You don’t let mother or anyone else make you conform to someone you’re not. No one gives you enough credit for that. I admire that about you Sirius.” When you turned to face him it was then you viewed him in an entirely different light, literally. The afternoon glow of a dying sun cast an orange haze over him, making Sirius appear incredibly warm and his pale skin stand out even more. There was a small pitter patter in your chest. Something you hadn’t felt before. With Regulus you hadn’t fallen in love with him. You had always loved him in that way. There hadn’t been a sudden realization. It had always just been there. 

With Sirius though you had gotten the opportunity to fall in love. 

And oh, how it was something beautiful. 

You suppose it was weird, falling in love with another brother. To be honest, you couldn’t imagine feeling safer around anyone else. Your parents had coddled you too much and kept you locked inside Grimmauld Place for so many years that you didn’t know how to properly interact with other kids your age. All you had known were Sirius and Regulus. In retrospect it made sense. Odd and weird as it was, it made sense to you. 

Sirius did everything he would with any other girl to win you over. But you weren’t just any other girl. No, you were more important. He made his wooing efforts even more special. 

You liked it. Regulus had never done such a thing to win you over. He never had to. It was nice to know that someone was willing to go through all that effort for you. 

Knowing that you were still tender and healing from Regulus ignoring you, Sirius took things slow. Something that you knew was completely unheard of for your brother. He had to take more care though, you were his sister above all things. The last thing Sirius wanted to do was make things difficult for you or hurt you in any way. It made you love him even more. 

After a month or so of Sirius courting you in secrecy (which was hard for Sirius since he liked making grand gestures in public), Regulus decided to start talking to you again. 

You wouldn’t let him back in that easily. You lashed out at him just as much as he had with you that fateful day. And he took it all with no complaint. Regulus hung his head in shame. 

“I know. I’m sorry (y/n). It’s just the thought of Sirius. . . The thought of Sirius being in love with you, it upset me.” Regulus murmured then lifted his eyes up to you. “It made me crazy. I don’t like that he feels that way about you. You’ve always had a soft spot for him.” 

“That’s no excuse.” You cross your arms unhappily, glaring at him with as much heat you could muster. Many times Sirius had teased you that when you glared like that you looked like Walburga, your mother. Pushing that fact out of your mind, you take a predatory step forward that makes Regulus visibly flinch. You were sweet as pie normally, but if someone made the wrong move against you, well, it wasn’t a pretty sight. You had taken after your mother in more than one regard. You looked even more deadly with your wand gripped tightly in your hand. “Regulus, I love you but things have changed now. You shut me out. You hurt me. Broke my heart. For what? For nothing.” 

Eyes grow wide, staring at you with disbelief. “(y/n). . . Don’t. . .” 

“Sirius was with me the entire time. Unlike you.”

You knew the effect that would have on him. Utter devastation. Immediately you saw it as his face crumbled. It was painful to see him like that and even more to know that you had done that to him. You hadn’t said it to be mean, no, despite how much Regulus had hurt you you wouldn’t stoop to being spiteful. 

“So. . . You were. .. You were in love with him.” Pain made his voice crack. 

“No. Not originally. But you hurt me Regulus. And Sirius was there to comfort me. He’s been nothing but sweet to me and now I’m pretty sure that he would never hurt me the way you have.” 

Regulus’ chest rose and fell as he struggled to stay calm. Red rimmed the outside of his eyes and you felt your heart breaking all over again. Even though you were extremely upset with him he was still your brother who you loved dearly. 

“You hurt me Regulus. . .” Was all you could say to him as you turned back around to walk away from your twin. 

“Wait (y/n)!” A hand reaches out to you and pulls you back to him. You could feel the warmth of his chest seep into your back as he held you, his arms crossed over your chest as you keeps you there. 

“Please. . . I don’t want to lose you because I was stupid. . . Tell me there’s some way I can make up for what I’ve done. . . I don’t want to lose you to Sirius.” 

Truth was you had already kissed Sirius a few days ago. It would break his heart for you to suddenly drop him.  
  
  


And it was that situation that had the three of you in the Room of Requirements together. 

You couldn’t give up either of them so there had to be a compromise. And neither of your brothers wanted to step down. Regulus had been about ready to fight Sirius for you but you didn’t want that either. There was already a rift between the two brothers far before they had affection for you. You didn’t want things to become even more terrible between them. 

To stop them from bickering further you pull away slightly from Sirius to kiss Regulus’ jawline, coaxing his lips towards your own as your hand lovingly rubbed against Sirius’ trousers. 

“No more fighting.” Your voice was low, palm sensually rubbing Sirius until you could feel him get hard. “Remember what happens when you don’t keep your promise?” 

They had taken an oath not to fight one another. If they broke it then no one got you. 

Regulus huffs but you know he won’t argue anymore. Sirius was content to lean back and let you keep rubbing him with a coy grin on his face. 

“I’m not fighting. Are you Regulus?” 

“No.” Regulus takes your free hand to kiss each individual knuckle. “No, I’m not fighting.” 

“Good. Then we can move on to the good stuff.”


End file.
